Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/me2resh/apexyard/dfdnpx skills add me2resh/apexyard --skill dfdgit clone --depth 1 https://github.com/me2resh/apexyardWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00030 | $0.05140 |
| Opus 5 | $0.00015 | $0.02570 |
| Sonnet 5 | $0.00006 | $0.01028 |
| Haiku 4.5 | $0.00003 | $0.00514 |
Grade A, and why
dfd scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 351 lines — stays where its author put it; the contents beside it link to each section on GitHub.
/dfd — Data Flow Diagram Extractor
Reads a codebase (or a portfolio of codebases for system-wide DFDs) and produces a Data Flow Diagram showing external actors, processes, data stores, data flows, trust boundaries, and per-element data classifications. The DFD is the input to STRIDE threat modelling and to GDPR cross-border / DPA-coverage analysis.
This skill is the canonical DFD producer in the apexyard family. /threat-model and /compliance-check consume the DFD it writes instead of regenerating their own — see AgDR-0026 for the design rationale.
| Skill | Role |
|---|---|
/dfd (this skill) |
Produces the DFD — six-axis discovery + classifications + cross-repo trace |
/threat-model |
Consumes the DFD — STRIDE walk over each trust-boundary crossing |
/compliance-check |
Consumes the DFD's classifications — cross-border transfers + DPA coverage |
/c4 |
Static topology (different shape — system + containers, no data-flow semantics) |
/process (#256) |
Dynamic control flow — BPMN, anchor-scoped multi-repo trace (shares the _lib-multi-repo-trace.sh helper) |
Path resolution
Read the registry path via portfolio_registry, the per-project docs dir via portfolio_projects_dir, and the workspace dir via portfolio_workspace_dir from .claude/hooks/_lib-portfolio-paths.sh. Cross-repo discovery uses the shared _lib-multi-repo-trace.sh helper. Source both at the top of any bash block:
source "$(git rev-parse --show-toplevel)/.claude/hooks/_lib-read-config.sh"
source "$(git rev-parse --show-toplevel)/.claude/hooks/_lib-portfolio-paths.sh"
source "$(git rev-parse --show-toplevel)/.claude/hooks/_lib-multi-repo-trace.sh"
projects_dir=$(portfolio_projects_dir)
Defaults match today's single-fork layout. Adopters in split-portfolio mode override the portfolio.* keys in .claude/project-config.json — the helper resolves whichever mode they're in. See docs/multi-project.md.
Usage
/dfd # interactive — asks for scope (single service or system-wide)
/dfd billing-api # registered project — single-service DFD
/dfd . # treat cwd as the project root
/dfd --scope-all # walk the whole registry — system-wide DFD with per-service sub-models
/dfd billing-api --format=dragon # also emit Threat Dragon v2 JSON
/dfd billing-api --format=all # Mermaid + Threat Dragon + (future) PlantUML
What ships with it
7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 351 lines · 30 tokens per session scan A ba00e131f3ca
dfd is a skill published in the GitHub repository me2resh/apexyard (497 stars, last pushed 3d ago), licensed MIT. It adds 30 tokens to every session and 5,140 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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